When talking about a theoretical situation in the past - in the present case this sentence: "It is because those people (theoretical) would not have had been (action) - is it correct to use "have had been"?
There may be some dialects that use this, but it's not grammatical in any standard English that I am aware of.
Auxiliary have can be followed by the past participle of the main verb:
They have seen him.
They have had dinner.
or by been (ppt of "be") for continuous or passive:
They have been seeing him.
The have been seen by him.
but not by any other auxiliary